Investigations into a gunrunning sting gone horribly wrong are creeping closer to the top of the U.S. Justice Department and its head, U.S. Attorney General Eric H. Holder, Jr.

New documents, released this week, indicate that Holder may have lied to Congress about how much and when he knew about the sting, known as Operation Fast and Furious, in which U.S. Bureau of Alcohol, Tobacco, and Firearms (ATF) agents allowed more than 2,000 firearms to "walk" across the U.S. border to Mexico and into the hands of Mexicoâs brutal drug cartels.

As many as 1,700 of those weapons have since been lost, and more than 100 have been found at bloody crime scenes on both sides of the border, including at the murder site of a U.S. Border Patrol agent in Arizona last December. The sting is now the subject of a Congressional investigation to find out who was responsible for or knew about the operation.